Electromagnetic vibratory device



March 22,-1932. PAYNE 1,850,848

ELECTROMAGNETIC VI BRATORY DEVICE Filed eb; 16, 1929 4 i 5. i i

"Jnventor- Ottorneys.

Patented Mar. 22, 1932 UNITED STAT-ES PATENT OFFICE.

EDWIN manconm PAYNE, or SOUTHALL, ENGLAND, ASSIGNOR, BY mEsNE ASSIGN- mnnrs, 'ro RADIO CORPORATION or AMERICA, or NEW YORK, N. Y., A conroaa- TION OF DELAWARE Application filed February 16, 1929, Serial No.

The present invention relates to electromagnetic vibratory devices, such for example as telephone reproducers or devices for recording sound or for reproducing recorded sound, in which an armature of magnetlc material is adapted to vibrate towards and away from one or more magnetic poles.

According to the present invention an electro-magnetic device comprises an armature mounted for. vibration towards and away from a magnet pole wherein the surface of the armature adjacent the magnet pole is other than flat, the co-operating surface of the magnet pole being shaped to correspond. In this way the stiffness/mass ratio of the armature can be greatly increased without loss of electro-magnetic efiiciency. The invention is illustrated in the'accompanying drawings as applied'to a device for convertmg a soundtrace upon a d1sc record into corresponding electrical oscillations.

Figs. 1 and 2 are views in plan and elevation respectively of an armature in accordance with'the invention and system in accordance with the invention.

The magnet fisystem comprises two U- shaped permanent magnets 1 and 2 arranged with'their poles 3, 3and 4, 4' respectively pointing inwards and with the North pole of one opposite the South pole of the other.

The armature comprises a boss 5 provided with pivot holes 6 with the aid of which the armature is pivotally mounted on the magnet system. The axis of vibration of the arma= ture isindicated in Figs. 1, 2 and 4 by the reference 7. The armature may be shaped in such a manner as to increase its inherent rigidity or stiffness to internal vibration without substantially increasing its mass, preferably by means of corrugations or ribs extending in a direction to stiffen the armature against internal vibration. In the form shown, working blade 8 of the armature is ribbed or corrugated in a direction perpen dicular to the axis 7. Suitable means may be provided for clamping a reproducing stylus in the projecting member 9. The working surfaces of thetwo-magne't poles 3, 4 are shaped to correspond with the corruga- Figs. 3 and 4 are similar views of a magnet- ELECTROMAGNETIC VIBRATORY DEVICE 340,569, and in Great Britain March 21, 1928.

As shown in Fig. 4 damping pads 10 of rubher or other suitable material may if desired be arranged upon suitable brackets 11 carried upon the upper side of the upper poles 3 and 4 and bear upon the two sides of anextension of the armature blade 8. The cor.- rugationsmay be continued along this extension and a greater damping surface is then offeredthan if the extensionpiece were flat.

A suitable coil (not shown) is arranged around the armature blade 8 and vibrations of the armature blade 8 generate electr0-mo.-. tive forces in this coil in known manner.

' In the arrangement described the armature blade is of constant thiclmess but the invention is not limited to such an arrangement.

I claim:

1. An electromagnetic vibratory device comprising a magnet, and an armature mounted for vibration and cooperating therewith, said armature being provided with stiffening corrugations to prevent internal vibrations thereof and, the pole face of said magnet being shaped to correspond with the corrugated surface of the armature.

2. An electromagnetic vibratory device comprising a magnet, and an armature mounted to vibrate to cooperate with said magnet, said armature being provided with stiffening corrugations extending in the direction of propagation of internal vibrations in said armature, and the pole face of said magnet being shaped to correspond with the corrugated surface of said armature.

3. An electromagnetic vibratory device comprising a magnet and a vibrating armature pivotally mounted to cooperate therewith, said armature being rovided with stiifening corrugations extending perpendicular to the pivotal axis thereofand the pole face of said magnet being shaped to correspond with the corrugated surface of the armature.

4. In a device of the class described, the combination of a corrugated armature of 100 substantially constantthickness, the corruga'tions extending in a direction to impart stiffness against internal vibration, and a co operating magnet having a pole face shaped to correspond with said corrugations.

5. In a device of the class described, the combination of a pivoted armature of substantially constant thickness and having corrugations extendin at right angles to the pivotal axis thereo and a magnet having a poleface shaped to correspond with the corrugated surface of said armature.

6. In a device of the class described, the combination of a vibrating armature having corrugations extending in a direction to impart stiffness against, internal vibration, a cooperating magnet having a pole face shaped to correspond withsaid corrugations, and damping means engaging the corrugated surface of said armature.

7. In a device of the class described, the

combinationof a vibrating armature pivotal- 7 1y mounted and provided with stifiening corrugations extending perpendicular to the pivotal axis thereof, a magnet cooperating with said armature and having a pole face shaped to correspond with the corrugated surface of the armature, and damping means engaging the corrugated surface of the armature.

8. An electro-magnetic vibratory device comprising a magnet and an armature mounted for vibration about an axis toward and away from a pole of said magnet, the crosssectional form of said armature in a plane parallel to said axis being non-rectangular,

whereby the surface opposed to the magnet pole is non-planar, and the said pole being shaped to correspond to said surface.

In testimony whereof I have signed my name to this specification.

EDWIN MALCOLM PAYNE. 

